Method for providing uniform radial clearance of labyrinth seals between rotating and stationary components

ABSTRACT

Arcuate seal segments have radially directed seal faces forming part of a labyrinth seal in a turbine. The segments are adjustably spaced from the locating flanges of the groove formed on a stationary part of the turbine housing to compensate for any distortion of the groove through use. In a positive pressure, variable clearance labyrinth seal, side seals are disposed between the locating flanges of the groove and the flanges of the seal segments and have surfaces at circumferentially spaced positions which are adjustable to maintain concentricity of the seal faces of the seal segments, notwithstanding the distortion of eccentricity of the groove and its locating flanges. Where the locating flanges of the segments normally engage the locating flanges of the groove, variable clearances are provided between those flanges by the interposition of dowels, plugs or pads such that the seal faces of the segments are maintained concentric, notwithstanding distortion of the locating fits.

RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.07/927,920, filed Aug. 12, 1992, now abandoned by LeRoy D. Jewett andEarl H. Brinkman, for APPARATUS AND METHODS FOR MAINTAINING THECONCENTRICITY OF SEALS BETWEEN ROTATING AND STATIONARY COMPONENTS,which, in turn, is a continuation application of Ser. No. 07/696,760,filed May 7, 1991, now abandoned, by LeRoy D. Jewett for "APPARATUS FORMAINTAINING THE CONCENTRICITY OF SEALS BETWEEN ROTATING AND STATIONARYCOMPONENTS," the disclosures of which applications are incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates to seals between rotating and stationarycomponents of a machine, for example, a steam turbine, and particularlyrelates to apparatus and methods for ensuring concentricity of astationary seal face about the sealing surface of a rotating component,i.e., ensuring a substantially uniform radial clearance about andbetween the stationary seal face and the rotary component, in the eventthe stationary seal support structure is distorted or out-of-round,eccentric or non-standard in size. The present invention thereforeattains the heretofore unattainable uniform seal to rotor radialclearance in the presence of a locating fit for the stationary seal facewhich is out-of-round, eccentric to the axis of rotation, or a custom oroff-standard size. The present invention compensates for these factorsin the stationary support structure without compromising the geometricalconcentricity of the stationary seal face about the rotating sealingsurface.

BACKGROUND

In many machines, seals are provided between rotating and stationarycomponents. For example, in steam turbines, it is customary to employ aplurality of arcuate seal ring segments to form a labyrinth seal aboutand between the stationary and rotating components. Typically, thearcuate seal ring segments are disposed in an annular groove in thestationary component designed to be concentric about the axis ofrotation of the machine and hence concentric to the sealing surface ofthe rotating component. Each arcuate seal segment carries an arcuateseal face in opposition to the sealing surface of the rotatingcomponent. In labyrinth-type seals, the seal races carry aradially-directed array of axially spaced teeth, and which teeth areradially spaced from an array of axially spaced annular grooves formingthe sealing surface of the rotating component. Alternatively, therotating component may have a smooth surface in radial opposition to thearray of teeth on the seal faces. In any event, the sealing function isachieved by creating turbulent flow of a working media, for example,steam, as it passes through the relatively tight clearances within thelabyrinth defined by the seal face teeth and the opposing surface of therotating component.

In a typical installation, the annular groove is dovetail-shaped, havinglocating flanges directed axially toward one another and defining a slottherebetween. The stationary component is split lengthwise such that thesemi-annular dovetail grooves may receive correspondingly-shaped arcuateseal ring segments. More particularly, the arcuate segments aresimilarly dovetail-shaped, having a pair of flanges directed axiallyaway from one another for disposition within the dovetail groove and aneck joining the seal face and the flanges of the segment and passingthrough the slot defined by the locating flanges of the groove. The neckcarries the arcuate seal face radially inwardly of the groove wheninstalled.

In this type of seal, the ability to maintain a tight uniform clearancewithout physical contact between the rotating and stationary componentsis critical to the formation of an effective seal. If this radialclearance between the seal faces of the segments and the opposing sealsurface of the rotating component becomes too large, less turbulence isproduced and the sealing action is compromised. Conversely, if theclearance is too tight, the sealing teeth may contact the rotatingelement, with the result that the teeth lose their shard profile andtight clearance and thereafter create less turbulence, likewisecompromising the sealing action.

Seals of this type often do not obtain the designed uniform radialclearance about and between the stationary and rotating components for anumber of reasons. For example, the locating fits, i.e., the locatingflanges of the stationary component, may be distorted or out-of-round,relative to the sealing surface of the rotor. Conversely, the locatingfits may be perfectly round but lie eccentric to the sealing surface andaxis of the rotary component. The radial clearance between thestationary seal faces and the sealing surface of the rotating component,in either case, will not therefore be uniform about the rotor axis.Thirdly, the locating fit may be a custom size or non-standard in size.Even though round, it may not provide the designed radial clearancebetween the stationary and rotating components when the seal ringsegments are replaced. Of course, various combinations ofout-of-roundness, eccentricity and non-standard sizes may occur.

Turning first to the locating fits which have become distorted orout-of-round, e.g., as a result of high-pressure and temperatureapplications, such distortion directly affects the dimensionalconsistency of the labyrinth seal's internal clearance and thus theseal's effectiveness. In most instances, the locating flanges willdistort, with an opening effect on one axis which will result in aclosing effect on a perpendicular axis. For example, the locatingflanges on the stationary component tend to be deformed into anelliptical configuration which prevents the formation of a uniform sealclearance about the rotating component. The magnitude of the ellipticitypresent translates directly into excessive clearance of the seal facesof the segments relative to the sealing surface of the rotor across themajor diameter of the elliptical bore and minimum clearance across theminor diameter of the elliptical bore. The seal clearances thus varyfrom a condition of interference on one axis and excessive clearance onthe other, resulting in loss of the effectiveness of the seal.

As noted previously, the locating fits may themselves be round, but dueto variations in alignment they may not lie concentric to the sealingsurface of the rotating component. As a consequence, the seal faces ofthe segments may lie eccentric to the locating fits, i.e., the locatingflanges, but do not afford a uniform radial clearance between thestationary seal faces and the sealing surface of the rotating componentabout the full circumference of those components. Also, where thelocating flanges are non-standard or of unknown dimension due to priorfield machining, standard seal segments may not provide the designeduniform radial clearance even if the locating flanges are perfectlyround. The seal clearances must be maintained substantially uniform andat the designed clearance.

When renewing labyrinth seals of this type after use, the design of thelocating flanges of the groove into which the arcuate segments fitprevent their ready adjustment in radial location. Restoration of thelocating flanges of the groove is too costly. Typically, when newarcuate seal segments are installed into a groove where the locatingflanges are distorted or out-of-round, or eccentric, the installercarefully identifies the locations where the seal clearance is tootight. Once identified, the installer hand-scrapes or grinds the edgesof the seal teeth to produce the necessary clearance. No remedial actionis typically taken where the seal tooth-to-rotor clearance is excessive.This excessive clearance is conventionally left in an as-is condition.Because of the time and expense involved in the restoration of thelocating flanges of the groove to true concentricity about the rotorsurface, excessive seal clearances were simply heretofore accepted as aparasitic loss associated with age and distortion and not repaired.

These problems are extant both for conventional labyrinth seals, i.e.,where the locating flanges of each arcuate seal segment engage directlyon the locating flanges of the groove and springs bias the segment forradial inward movement, as well as for positive pressure variableclearance type, labyrinth seals, where the arcuate seal segments aremovable radially relative to the groove to control, adjust or vary theclearance between the seal faces of the stationary component and therotary component in response to changes in operating conditions of therotary machine. An example of the latter type of labyrinth seal isdescribed and illustrated in co-pending application Ser. No. 07/257,471,filed Oct. 13, 1988, of common assignee herewith, now U.S. Pat. No.5,002,288, the disclosure of which is incorporated herein by reference.The foregoing problems are cured by the present invention.

DISCLOSURE OF THE INVENTION

According to the present invention, there is provided apparatus andmethods providing for substantially uniform radial clearance about andbetween the seal surfaces of the stationary and rotating components wheninstalling arcuate packing ring segments in rotary machines employinglabyrinth seals without compromising the integrity or efficiency of theseal. More particularly, replacement arcuate segments are provided withlocating or hook flanges concentric to the axis of rotation of themachine. By altering the clearance, however, between the locatingflanges of the arcuate segments and the locating flanges of the grooveabout the axis of the machine, any distortion, or out-of-roundness,eccentricity or non-standard size of the locating flanges of the grooveare taken into account and the arcuate segments may thus be installedwith their seal faces substantially concentric with the sealing surfaceof the rotor shaft.

To accomplish this in conventional labyrinth seals, locating elementshaving locating surfaces are spaced along the locating flanges of thearcuate segments. These locating elements may be provided in a number ofways. For example, dovetail-shaped elements, e.g., T-shaped blocks orpads, may be provided for disposition in complementary shaped keywaysformed in the segments. The locating surfaces of the elements projectbelow the locating flanges of the segments and are adjustable, e.g., bygrinding, to an appropriate depth, to adjust the clearance between thelocating flanges of the segment and groove thereby to maintainconcentricity of the stationary and rotating seal faces whilesimultaneously mounting the arcuate segments directly on the distorted,eccentric or non-standard size locating flanges of the groove. Inanother form, the arcuate segments may be provided with axiallyextending dowels extending below the surfaces of the flanges of thesegments. The dowels may be machined to variably space the segmentflanges from the distorted, eccentric or non-standard size locatingflanges of the grooves to establish and maintain the desired uniformradial clearance of the stationary seal faces relative to the sealingsurface of the rotor. Other types of pins or pads may be employed andhave locating surfaces adjustable to adjust the spacing between thesegment and groove locating flanges. In these embodiments, the spacingmay be adjusted by the addition or subtraction of material at variouspredetermined locations or combinations of additive and subtractivematerials may be employed. Also, the locating elements can be radiallydisplaced relative to the segments to adjust the locating surfaces.

In the case of positive pressure variable clearance-type seal segments,springs are provided below the segment locating flanges and engage thegroove locating flanges to bias the segments radially outwardly.Locating elements are provided in the groove, preferably carried by theflanges of the segments as in the conventional type labyrinth sealsdiscussed above, and have locating surfaces disposed below the segmentflanges for engagement with the locating flanges of the groove. Byadjusting the location of these surfaces in a radial inner direction,i.e., by adding material to the surfaces, or in a radial outwarddirection, i.e., by removing material from the surfaces, or by otherwisedisplacing the locating surfaces, the seal faces of the segments aremaintained in substantially uniform and designed radial clearancerelative to the sealing surface of the rotor.

In certain other positive pressure packing ring segment applicationswhere the segments are exposed to high fluid pressure, side seals areemployed. These side seals form spacers or buffers between the locatingflanges of the arcuate segments and the locating flanges of the groove.In accordance with the present invention, contact or locating surfacesbetween the aide seals and the locating flanges of the arcuate segments(or between the side seals and the locating flanges of the groove) canbe altered, for example, by grinding, or adding material, to compensatefor the distorted, eccentric or non-standard size of the locatingflanges of the groove thereby to maintain a uniform radial clearancebetween each arcuate seal segment face and the sealing surface of therotary component. This adjustment can be accomplished uniformly in thecase of custom or non-standard sizes or non-uniformly in the case ofout-of-roundness or eccentricity of the locating flanges of the groove.That is, the adjustable spacing is provided by adjusting the radialextent of the locating surfaces of the side seals at circumferentiallocations about the segments in accordance with the measured distortion,eccentricity or non-standard size of the fit or groove at correspondingcircumferential locations about the fit or groove. In this manner, auniform clearance is maintained between the segment seal faces of thepositive pressure packing ring relative to the sealing surface of therotating component, notwithstanding the distortion, eccentricity, ornon-standard size of the locating fit or flanges of the groove.

Consequently, the present invention provides for initial installation orreplacement of conventional or positive pressure arcuate seal ringsegments in a rotary machine in a manner enabling compensation forstationary support distortion, eccentricity or non-standard sizeswhereby a uniform designed radial clearance between the segment sealfaces and the sealing surface of the rotor shaft is obtained.

Seals between rotating and stationary components have also employedarcuate half-ring segments. In seals of this type, each segment has alocating flange projecting to one side of its neck and a sealing flangemounting the sealed teeth projecting from the same side of the neck ofthe segment. A corresponding fit in the stationary component is providedin the form of a groove having a single axially directed locatingflange. Locating elements are provided on the one side of the segmentand have locating surfaces in the groove which can be adjustedsimilarly, as previously described, to establish a substantially uniformradial clearance about and between the rotating component and thesegmented seal faces.

The present invention may also be applied to seals formed elsewhere in amachine have rotating and stationary components. For example, in aturbine, the rotating buckets are normally provided with a bucket coverwhich forms a seal with a stationary tip spill strip segment mounted ina stationary portion of the machine. The tip spill strip segment isconventionally mounted in a single locating hook or flange in a mountinggroove by locating the segment flange against the groove locatingflange. In accordance with the present invention, the existing flangecan be machined and locating elements placed in the segment atcircumferential positions about the segment such that locating surfacesare disposed between the segment flange and the groove flange. Byadjusting these locating surfaces, i.e., by adding material orsubtracting material, or displacing them, to vary their radial location,the distortion, eccentricity or non-standard size grooves can becompensated for to establish and maintain uniform radial clearancebetween the tip spill strip segment and the bucket vane cover.

Accordingly, in accordance with a preferred embodiment of the presentinvention, there is provided, in a machine having rotating andstationary components formed about an axis, a seal comprising an annulargroove formed in the stationary component including at least one axiallydirected locating flange about the axis and in part defining a slotopening into the groove, the seal further including about the machineaxis a plurality of arcuate segments each having an arcuate seal face, aneck portion received in the slot and at least one axially directedflange disposed within the groove and spaced radially from said locatingflange, and locating elements in the groove between the flanges of thesegments and the locating flange at spaced circumferential positionsabout the axis, the locating elements being adjustable in a radialdirection to enable adjustment of the radial spacing between thelocating flange and the flanges of the segments thereby establishing asubstantially uniform radial clearance about and between the rotatingcomponent and the segment seal faces.

In another preferred embodiment of the present invention, there isprovided, in a machine having rotating and stationary components formedabout an axis, a seal comprising an annular groove formed in thestationary component and including a pair of locating flanges about theaxis and directed axially toward one another defining a slottherebetween, the seal further including about the machine axis aplurality of arcuate segments each having an arcuate seal face, a neckportion received in the slot and a pair of flanges directed axially awayfrom one another and disposed within the groove, the flanges of thesegments and the locating flanges of the grooves being radially spacedfrom one another, and locating elements in the groove between theflanges of the segments and the locating flanges at spacedcircumferential positions about the axis, the locating elements beingadjustable in a radial direction to enable adjustment of the radialspacing between the locating flanges of the groove and the flanges ofthe segments thereby establishing a substantially uniform radialclearance about and between the rotating component and the segment sealfaces.

In a further preferred embodiment of the present invention, there isprovided for installation in a machine having rotating and stationarycomponents formed about an axis wherein the stationary component has anannular groove including at least one axially directed locating flangeabout the axis and in part defining a slot opening into the groove, anarcuate seal segment having an arcuate neck portion for reception in theslot, an arcuate seal face extending axially to one side of the neckportion and along a radially innermost portion of the segment and atleast one hook flange directed axially to one side of the neck portionalong a radially outermost portion of the segment for disposition withthe groove. The hook flange and the arcuate seal face being radiallyspaced from one another, and locating elements are carried by thesegment at spaced circumferential positions along the segment on the oneside of the neck portion, the locating elements having locating portionsradially inwardly of the hook flanges adjustable in a radial directionto enable adjustment of the radial spacing between the hook flange andthe locating flange of the stationary component thereby to establish,upon application of the segment to the stationary component, asubstantially uniform radial clearance about and between the rotatingcomponent and the seal face.

In a still further embodiment of the present invention, there isprovided, in a steam turbine having rotating and stationary componentsformed about a machine axis, a seal comprising an annular groove formedin the stationary component including a locating flange out-of-round oreccentric about the machine axis, a plurality of arcuate seal segmentsdisposed about the rotor axis and having seal faces forming a seal ringabout the rotor, and, means cooperable between the segments and theout-of-round or eccentric locating flange for adjusting segments inaccordance with the extent to which the locating flange is out-of-roundor eccentric about the axis to establish a substantially uniform radialclearance about and between the rotating component and the segment sealfaces.

In yet another embodiment of the present invention, there is provided ina machine having a component rotatable about an axis and a stationarycomponent including an annular groove about the axis, the stationarycomponent having at least one axially directed locating flange about theaxis and in part defining a slot opening into the groove and a pluralityof annular segments about the axis, each segment having an arcuate sealface, at least one axially directed flange for disposition in thegroove, and a neck portion receivable in the slot and interconnectingthe seal face and the flange of the segment, a method of compensatingfor deviation in radial clearance between the seal faces and therotatable component from a predetermined substantially uniform radialclearance therebetween comprising the steps of identifying the extent ofthe deviation of the locating flange of the groove from a predeterminedradial location thereof about the axis, and adjustably spacing theflanges of the segment relative to the locating flange of the groove inaccordance with the extent of the deviation of the locating flange ofthe groove from the predetermined radial location thereof about the axisto establish a substantially uniform radial clearance about and betweenthe seal of the segments and the rotating component.

In a still further embodiment of the present invention, there isprovided in a machine having a component rotatable about an axis and astationary component including an annular groove out-of-round oreccentric about the axis, the stationary component having a pair ofaxially inwardly directed locating flanges and a plurality of annularsegments about the axis, each segment having an arcuate seal face, apair of flanges directed axially away from one another and disposed inthe groove, and a neck portion received in the slot and interconnectingthe seal face and pair of flanges, a method of compensating forout-of-roundness or eccentricity of the locating flanges about the axis,comprising the steps of identifying the extent of out-of-roundness oreccentricity of the locating flanges of the groove, and adjustablyspacing the flanges of the segments relative to the locating flanges ofthe groove in accordance with the extent of out-of-roundness oreccentricity of the flanges of the groove about the axis such that theseal faces of the segments provide a substantially uniform radialclearance with the rotating component.

Accordingly, it is a primary object of the present invention to providenovel and improved apparatus and methods for maintaining a uniformradial clearance between the seal faces of a stationary componentrelative to the sealing surface of a rotating component in a mannerwhich compensates for any distortion or out-of-roundness, eccentricity,or non-standard size of the locating fit on the stationary supportmounting the seal faces.

These and further objects and advantages of the present invention willbecome more apparent upon reference to the following specification,appended claims and drawings.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a fragmentary cross-sectional view of a portion of a steamturbine looking transversely of the axis thereof and illustrating alabyrinth seal;

FIGS. 2A and 2B are schematic representations of upper and lowerportions of a turbine casing having out-of-round or elliptical fits forthe turbine seal;

FIG. 3 is a split cross-sectional view of portions of a fit for the sealof a rotor with the left quadrant illustrating an aspect of the problemsolved by this invention and the right quadrant illustrating a solutionto that problem according to the present invention;

FIG. 4 is a fragmentary cross-sectional view of a portion of a fit ofthe stationary component illustrating a sealing segment and locatingelements according to the present invention;

FIG. 5 is a top plan view of the seal segment illustrated in FIG. 4;

FIG. 6 is a cross-sectional view of the sealing ring segment of FIG. 4and illustrating a locating element secured thereto;

FIG. 7 is a view similar to FIG. 6 but illustrating a seal segmenthaving a single hook fit;

FIGS. 8 and 9 are respective transverse and axial fragmentarycross-sectional views illustrating a further embodiment hereof, withFIG. 9 being taken generally about on line 9--9 in FIG. 8;

FIGS. 10 and 11 are similar views as FIGS. 8 and 9 showing a furtherembodiment of the locating elements of the present invention;

FIGS. 12 and 13 are views similar to FIGS. 8 and 9 illustrating a stillfurther embodiment of the present invention;

FIGS. 14 and 15 are views similar to FIGS. 8 and 9 illustrating a stillfurther embodiment of the present invention;

FIGS. 16 and 17 are enlarged fragmentary cross-sectional views takentransversely of the axis of the turbine and illustrating a labyrinthseal of the positive pressure variable clearance packing type accordingto a further embodiment of the present invention in open and closedpositions, respectively, and taken generally about on lines 16--16 and17--17 in FIGS. 18 and 19, respectively;

FIGS. 18 and 19 are fragmentary axial cross sectional views illustratingthe labyrinth seal of FIGS. 16 and 17 in the respective open and closedpositions;

FIG. 19A is a schematic view similar to FIG. 19 on an exaggerated scaleto further illustrate the present invention;

FIG. 20 is an enlarged fragmentary view looking in the axial directionillustrating a further form of seal segments employing the locatingelements hereof;

FIG. 21 is a side elevational view of seal segments and locatingelements according to another embodiment of the present invention andlooking in the axial direction;

FIGS. 22A and 22B are enlarged schematic cross-sectional illustrationsof the juncture of the ends of leaf springs and locating elements andillustrating the manner of changing the deflection force of the springs;

FIG. 22C is an enlarged fragmentary elevational view looking in theaxial direction illustrating a joint between adjacent segments and a pinfor maintaining the segments in the upper turbine housing;

FIG. 23 is an enlarged fragmentary cross sectional view of a butt sealbetween adjacent ring segments;

FIG. 24 is a view similar to FIG. 20 illustrating a further form of thepresent invention;

FIG. 24A is a cross-sectional view thereof, illustrating a steam openingthrough the segment into the groove;

FIG. 25 is a perspective view of a sealing segment forming a seal aboutthe turbine bucket cover illustrated in FIG. 26 according to a furtherform of the present invention;

FIG. 26 is an enlarged cross-sectional view illustrating the mounting ofthe segment of FIG. 25 and its seal with the turbine bucket;

FIG. 27 is a side elevational view of a positive pressure packing ringsegment with side seals and compression tools applied thereto holdingthe segment in assembly; and,

FIG. 28 is a cross sectional view thereof taken generally about on line28--28 in FIG. 27.

DETAILED DESCRIPTION OF THE DRAWING FIGURES

Reference will now be made in detail to a present preferred embodimentof the invention, an example of which is illustrated in the accompanyingdrawings.

Referring now to FIG. 1, there is illustrated a portion of a steamturbine, generally designated 10, having a turbine shaft 12, disposed ina turbine housing 14, and which shaft is supported for rotation byconventional means, not shown, within turbine housing 14. Amultiple-stage labyrinth seal 16 includes a plurality of seal rings 18,20 and 22 disposed about turbine shaft 12 separating high and lowpressure regions 28 and 30 respectively. Each seal ring is formed of anannular array of a plurality of arcuate seal segments 32. In general,labyrinth seal 16 functions by placing a relatively large number ofpartial barriers to the flow of steam from the high pressure region 28to the low pressure region 30. Each barrier forces steam, attempting toflow parallel to the axis of turbine shaft 12, to follow a tortuous pathwhereby a pressure drop is created. The sum of all the pressure drops inthe labyrinth seal 16 is, by definition, the pressure difference betweenthe high and low pressure regions 28 and 30.

As explained previously, one of the major problems associated with theinitial placement of the annular sealing rings and their maintenance,including refurbishing and replacement, is the necessity to maintain theseal ring segments 32 concentric about and with seal faces at a uniformradial clearance with the sealing surface of the rotor, notwithstandingany distortion, eccentricity or non-standard size of the locating or fitflanges of the groove which form part of the housing for the seal rings.That is, the locating flanges of the seal ring support structure,oftentimes with use and wear, obtain an ellipticity or an eccentricitywith respect to the rotor axis whereby fitting the seal ring segments tothe locating flanges results in a lack of and non-uniform radialclearance between concentricity of the seal faces and the sealingsurface of the rotor. Also, even if the locating flanges are round andcoaxial with the rotor shaft, the desired uniform radial clearance, forexample during replacement of the segments, may not be obtained due tothe non-standard size of the locating fit. The present, inventiontherefore affords and maintains a uniform radial clearance between theseal faces of the segments and the sealing face of the rotor,notwithstanding any out-of-roundness or eccentricity of the locatingflanges of the turbine housing due to use and wear or a non-standardsize of the locating flanges and affords such uniform radial clearanceand concentricity in both conventional and positive pressure variableclearance type labyrinth seal rings.

To illustrate the problem solved by the present invention, andspecifically with respect to an out-of-roundness condition in thestationary support structure, reference is made to FIGS. 2A and 2B andto the left side of FIG. 3. In FIG. 2A, there is schematicallyillustrated upper and lower portions 14A and 14B, respectively, of aturbine housing. The locating fit for the arcuate ring segments isillustrated at F and, of course, the rotor shaft lies within fit F. Overtime, e.g., with variations in temperature and pressure and otherfactors, the rotating fit F may come out-of-round and typically obtainsan elliptical configuration, for example, the configuration of FIG. 2Awith major and minor axes V and H, respectively, where V is greater thanH. As illustrated in FIG. 2A, this sometimes occurs along the horizontaljoint between turbine housing portions 14a and 14b with the jointtending to open along the radial interior of the casing 14 forming theelliptical fit F. In FIG. 2B, the distortion of the locating fit F issimilarly elliptical but with the major axis H lying horizontal, H beinggreater than the minor axis V. In this situation, the horizontal jointopens radially outwardly of the casing 14. In either case, the fit F forreceiving the arcuate seal ring segments 32 is distorted andout-of-round. Of course, variations in the fit F may occur which are ofdifferent configurations than elliptical and these likewise areaccommodated by the present invention.

The elliptical configuration of the upper quadrants illustrated in FIG.2B is illustrated in more detail in FIG. 3. It will be appreciated thatthe FIG. 3 illustration is exaggerated and certain elements are out ofproportion relative to other elements to illustrate the nature of theproblem and its solution according to the present invention.

With respect to FIGS. 1 and 3, the arcuate seal ring segments 32 havesealing faces 34 and radial projecting teeth 36, each sealing face 34being formed by a pair of flanges 38 extending axially away from oneanother. The outer portions of the seal ring segments 32 includelocating flanges or hooks 40 which similarly extend from segment 32 inaxially opposite directions away from one another. As illustrated inFIG. 1, the turbine housing 14A has a generally dove-tail shaped annulargroove 42 defined along its radially innermost portions by a pair oflocating flanges 44 which extend axially toward one another defining aslot 46 therebetween.

Referring now to the left side of FIG. 3, it will be seen that, with theellipticity illustrated in FIG. 2B, the locating flange 44 of the fit Fis distorted, i.e., out-of-round. That is, the distance V/2 in thevertical direction from the rotor axis to flange 44 is less than thedistance H/2 in the horizontal direction from the axis of rotor 12 toflange 44. With segments 32 lying along arcs of circles, it will be seenthat the locating fits of segment flanges 40 and groove flanges 44 donot match and that, as a consequence, seal faces 34 have differentradial clearances α and β at different circumferential locations withrespect to the sealing face of rotor 12. Seal faces 34 do not thereforehave uniform radial clearances with respect to the shaft.

To provide a uniform radial clearance between the seal faces of thesegments and the sealing surface of shaft 12 in accordance with thepresent invention, reference is made to the right-hand side of FIG. 3.In this illustration, locating flange 44 of the groove fit F has thesame ellipticity as illustrated in FIG. 2B and is the mirror image ofthe left side of FIG. 3. However, means are provided in accordance withthe present invention for enabling adjustment of the radial spacingbetween the locating flange 44 and the locating flange 40 of thesegments 32 to establish a substantially uniform radial clearance aboutand between the rotating component 12 and the segmented seal faces 34notwithstanding distortion, eccentricity or non-standard size oflocating flanges 44. Generally, the adjusting means includes locatingelements E have locating surfaces in the grooves between the segmentflanges and the locating flanges which can be adjusted in radial extent,e.g., by the addition or removal of material from the elements or bydisplacement of the elements of their locating surfaces. Preferably, thelocating elements E are carried by segments 32 at circumferentiallyspaced positions therealong with the locating surfaces lying in thegroove between the segment flanges and the locating flanges of thegroove, there being at least two elements per segment. The radialadjustment of the locating surfaces enables the locating flanges of thesegment and the locating flanges of the groove to be variably spacedfrom one another about the the circumference to compensate for anydistortion, eccentricity, or non-standard size of the locating flangesthereby to provide a uniform radial clearance between the segment sealfaces 34 and the sealing face of the rotor 12.

Based on the foregoing general description of the present invention,various embodiments of the invention will be described with respect tothe drawing Figures, wherein like reference numerals are applied to likeparts in the drawing Figures followed by the suffix "a," "b," "c," etc.,to distinguish among the various embodiments.

Referring now to a first embodiment of the present invention, there isillustrated in FIGS. 4-6 a labyrinth seal of the same generalconfiguration illustrated in FIG. 1 and incorporating the adjustingfeature of the present invention. The seal includes a plurality ofarcuate packing ring segments 32a arrayed about the machine axis, therebeing typically six segments. As previously described, each segmentcomprises an arcuate sealing face 34a, having a plurality of axiallyspaced teeth 36a extending radially inwardly therefrom, sealing face 34abeing formed by the inner circumferentially extending surface of sealring segment 32a defined by the pair of axially projecting flanges 38a.A pair of locating flanges or hooks 40a are provided along outermostportions of seal ring segments 32a and similarly extend from segments32a in axially opposite directions away from one another. Turbinehousing 14a, of course, has a generally dovetail shaped annular groove42a, defined along its radially innermost portions by a pair of flanges44a which extend axially toward one another defining a slot 46atherebetween. Seal ring segment 32a also includes a neck 48a whichinterconnects seal face 34a including flanges 38a with the radiallyoutermost flanges 40a and, when segment 32a is installed in the groove42a of housing 14, extends in slot 46a between flanges 44a. Segment 32aalso includes a leaf spring 72a having a radially inwardly turned end75a engaging in a slot along the outer surface of segment 32a. When thesegment is installed, the spring engages the roof of the groove 42a andbiases the segment for radial inward movement. The shaft 12, not shownin FIGS. 4-6, lies in radial opposition to the sealing ring faces 34a ofsegments 32a and has a plurality of grooves which are axially spaced onefrom the other and extend circumferentially about the shaft. The groovesalong the shaft cooperate with teeth 36a to form the turbulent flow pathfor the steam.

With reference to FIGS. 3-6 and in accordance with the presentinvention, there is provided for each segment, as illustrated, at leasta pair of locating elements E having locating surfaces 47a whichcooperate between the locating flanges 40a and 44a of the segment andgroove, respectively, to provide uniform radial clearance between thesegment seal faces 34a and the sealing surface of rotor 12. In theillustrated form, each locating element E comprises a generally T-shapedpad 71a which is received in a complementary formed slot 69a by slidingin the axial direction. The T-shaped slot 69a is formed axially throughthe locating flanges 40a and portions of the segment neck 48a. T-shapedpad 71a may have a counterbored opening for receiving a bolt 73 forsecuring pad 71a to the segment 32. Other methods of securing the pad71a to the segment may be provided. For example, as illustrated in FIG.5, material of the pad or segment may be peened into a correspondingopening in the respective segment or pad. Importantly, by extending slot69a into the neck portion 48a of segment 32a and securing pad 71a inslot 69a, it will be appreciated that the marginal faces 47a of pad 71amay bear on the locating flanges 44a below flanges 40a of segment 32a.Consequently, segment flanges 40a are spaced from the locating flanges44a of the groove by the T-shaped pads 71a. By selectively adjusting theextent to which the locating surfaces 47a of locating element E arespaced below the undersurfaces of flanges 40a, the distortion,eccentricity or non-standard size of the locating flanges of 44a may beaccommodated in a manner whereby segments 32a form a substantiallyperfectly annular array about the rotor axis with the seal surfaces 34ahaving uniform radial clearance about the sealing surface of rotor 12.By selectively grinding or adding material to the surfaces 47a to agreater or lesser extent or otherwise radially displacing surfaces 47ain accordance with the extent to which the groove is distorted,eccentric or of non-standard size at that circumferential location, theseal faces 34a of the segments are adjusted to provide a uniform radialclearance with the sealing surface of the rotor, notwithstanding anysuch distortion, eccentricity or off size of the locating flanges 44 ofthe annular groove fit.

Referring to FIG. 7, there is illustrated single hook seal ring segments32a' and a single hook groove fit wherein each has only one axiallyextending locating flange 40a' and 44a' respectively. As in the case ofthe previously described double hook segments and grooves, these singlebook segments and grooves encounter the same problems as previouslydiscussed and the same solution is applicable. For example, T-shapedpads 71a' are secured in complementary shaped slots 69a' in the singlehook segment 32a' and may be adjusted as previously described to afforda uniform radial clearance between the seal faces of the single hooksegments and the sealing surface of the rotor shaft.

Referring now to FIGS. 8 and 9, there is illustrated a seal segment 32b,which typically is maintained engaged against locating flanges 44b. Tocompensate for any out-of-roundness, eccentricity or non-standard sizeof locating flanges 44b about the rotor axis, a plurality of dowels 70may be disposed axially into each seal segment 32b at circumferentiallyspaced positions therealong and along opposite sides thereof. Dowels 70are disposed in preformed openings adjacent the juncture of theundersides of flanges 40b and the neck 48b of the seal segments. Theundersurfaces, i.e., the locating surfaces, of the dowels can beadjusted by reducing the material of or adding material to the dowels,or both, depending upon the adjustments necessary to compensate for theout-of-roundness, eccentricity or non-standard size of the flanges 44bat the various circumferential locations about turbine housing 14b. Asillustrated in FIG. 9, segments 32b are biased in a radial inwarddirection by a leaf spring 72b.

Referring now to FIGS. 10 and 11, a plurality of pads 74, for example,formed of a metal material, may be disposed along the undersides offlanges 40c of veal segments 32c. Pads 74 are disposed atcircumferentially spaced positions about each segment and a spring 72c(FIG. 11) biases the seal segment 32c into engagement with locatingflanges 44c. By appropriately adjusting the radial extent, i.e., thethickness, of pads 74, for example, by grinding or adding material, orboth, at circumferentially spaced positions about the segments, theclearance between the undersides of flanges 40c and the locating flanges44c, can be adjusted such that seal segments 32c combine to form anannular seal ring in substantially perfect concentricity about andhaving uniform radial clearance with the sealing surface of the rotor.

Referring now to FIGS. 12 and 13, a plurality of pins 76, each having anenlarged head 78, may be disposed in pre-drilled holes atcircumferentially spaced positions about seal segment 32d. The heads 78of pins 76 thus space the flanges 40d of the segments 32d from thelocating flanges 44d of the turbine housing 14. By adjusting thethickness of the heads 78, for example, by grinding or adding material,or otherwise displacing the heads, seal segments 32d may be formed tocomprise an annular seal ring substantially perfectly concentric aboutthe sealing surface of rotor 12, notwithstanding the out-of-roundness,eccentricity or non-standard size of the locating flanges 44d about therotor axis.

In FIGS. 14 and 15, seal segments 32e are provided with pins 80 formedin pre-drilled and tapped openings in flanges 40e of seal segments 32e.By varying the extent to which pins 80 extend radially from thepre-drilled holes into engagement with the outer surface of the locatingflanges 44e, the clearance between the flanges 40e and locating flanges44e may be adjusted at circumferentially spaced locations to ensureuniform radial clearance of the seal faces 34e about the sealing surfaceof the rotor, notwithstanding the out-of-roundness, eccentricity ornon-standard size of the flanges 44e.

The foregoing description with respect to FIGS. 4-15 disclose thepresent invention in the context of its application to conventionalpacking rings where springs bias the packing ring segments radiallyinwardly against the groove fit and, with the aid of the locatingelements in one or more of the various illustrated embodiments enablesthe seal faces of the segments to be maintained at a uniform radialclearance relative to the sealing surface of the rotor. In the ensuingdescription with respect to FIGS. 16-24, the present invention will bedescribed with respect to its application in positive pressure packingrings where one or more springs bias the packing ring segments forradial outward movement and fluid pressure, i.e., steam, is supplied todisplace the packing ring segments radially inwardly against the bias ofthe springs to form the seal face. FIGS. 16-20 disclose the applicationof the present invention to positive pressure packing ring segmentshaving side seals and which are used where the grooves encounter highfluid pressures. FIGS. 21-24 disclose the application of the presentinvention to positive pressure packing ring segments without side sealswhere the diaphragm sees a lower pressure.

Turning now to FIGS. 16-20, the present invention is illustrated in thecontext of a positive pressure variable clearance packing ring segmentwith side seal. FIGS. 16 and 18 illustrate the seal ring segments in aradially outermost open position, while FIGS. 17 and 19 illustrate theseal ring segments in a radially innermost closed position as a resultof positive displacement due to the fluid, e.g., steam, pressure as isclear from the above-mentioned U.S. Pat. No. 5,002,288. As in the priorembodiments, like parts are identified with the reference numeralsfollowed by letter suffixes.

As in the prior embodiments, each seal ring is comprised of a pluralityof arcuate packing ring segments 32f. Each segment 32f comprises a sealface 34f having a plurality of axially spaced teeth 36 extendingradially inwardly therefrom, a pair of flanges 38f extending axiallyaway from one another and mounting teeth 36f, a pair of locating flangesor hooks 40f which similarly extend from segment 32f in axially oppositedirections away from one another, and a neck 48f which interconnectsseal face 34f, including flanges 38f, with the radially outermostflanges 40f. It will be appreciated that the turbine housing 14f has agenerally dovetail-shaped annular groove 42f defined along its radiallyinnermost portions by a pair of locating flanges 44f which extendaxially toward one another defining a slot 46f therebetween. Shaft 12fhas grooves 50f which are cooperate with teeth 36f to form the turbulentflow path for the steam in this positive pressure variable clearancepacking ring seal. For a detailed discussion of the fluid pressuresacting on seal ring segments 32f whereby the seal ring is moved betweenopen and closed positions, reference is made to the above-identifiedU.S. patent.

In this packing ring, a pair of side seals 52f are provided for eachseal ring segment and which side seals 52f are located between flanges40f and 44f. Each side seal 52f is substantially coextensive in lengthwith its corresponding seal segment 32f and includes a radiallyextending locating rib 54f. Each rib 54f extends within a slot 56fformed through flange 40f of segment 32f. Crush ribs 58f are provided atcircumferentially spaced positions along each side seal 52f. Each sideseal 52f also includes an elongated recess 60f for seating a spring 62f.The opposite ends of spring 62f bear against the underside of flange40f, and its midsection bears against a central portion of recess 60fwhereby the side seal 52f is biased for radial inward movement.

In accordance with the present invention, each side seal 52f has aplurality of circumferentially spaced surfaces 64f for engaging theunderside of flanges 40f in a manner enabling adjustment of the radialclearance between the seal faces 34f to the sealing surface of rotor 12.With specific reference to FIGS. 16 and 18, it will be seen that, whenthe turbine is idle, springs 62f bias side seals 52f against the axiallyinwardly directed flanges 44f with the reaction force being provided bythe abutment of flanges 40f against turbine housing 14. Consequently, inthe position illustrated in FIG. 18, seal segments 32f lie in theirradially outermost positions.

When the steam pressure acts on the seal segments to displace thesegments radially inwardly as illustrated in FIGS. 17 and 19, flanges40f bear against the circumferentially spaced surfaces 64f of side seals52f. It will be appreciated from a review of both FIGS. 18 and 19 thatthe radially innermost surface of side seals 52f lies in continuousengagement along the outermost surface of locating flanges 44f.

In the event the locating flanges 44f are out-of-round, eccentric or ofnon-standard size, it will be appreciated that the various circular sealsegments 32f, because of their indirect engagement with the locatingflanges 44f through side seals 52f, would locate their seal faces 34f atdifferent radial clearances vis-a-vis the sealing surface of rotor 12.To prevent this, and in accordance with the present invention, theout-of-roundness, eccentricity or non-standard size of the locatingflanges 44f is initially determined. For example, if the locatingflanges 44f have assumed an elliptical shape, with the minor axispassing through rib 54f, it will be appreciated that flange 44f willassume a more flattened configuration than if it was round. Thisflattened configuration is illustrated in FIG. 19a in an exaggeratedview. FIG. 19a shows the adjustment of the segment according to thepresent invention with the segment in its closed condition. Thus, underpositive fluid pressure, and with locating flanges 44f having theaforedescribed ellipticity, the clearances between the segment flanges40f and the locating flanges 44f are different at circumferentiallyspaced positions thereabout as indicated at α and β where α is less thanβ. The side seals 52f are formed sufficiently flexible such that, underthe bias of springs 62f, their inner surfaces continuously engage theouter surfaces of the locating flanges 44f, notwithstanding anydistortion, e.g., flattening-out, of such surfaces. After the variationsin the clearances are determined, and to provide a designed uniformradial clearance between the seal surfaces 34f and the sealing surfaceof rotor shaft 12f, the surfaces 64f are adjusted in accordance with thepresent invention prior to installation of the segments, for example, bygrinding or adding material, such that surfaces 64f are concentric withflanges 40f thereby accommodating for the out-of-roundness and enablingthe sealing faces to have uniform radial clearance around the rotorshaft. As noted previously, material can be added and materialsubtracted from the various locating surfaces, or those surfaces may bedisplaced, depending upon the adjustment required to achieve thedesigned uniform seal clearance. In this manner, when seal segments 32fare displaced radially inwardly, e.g., by steam pressure, the circularundersurfaces of flanges 40f will engage the adjusted surfaces 64f ofside seals 52f whereby the sealing faces 34f of the seal rings will haveuniform radial clearance about the sealing surface of the rotor,notwithstanding the out-of-roundness, eccentricity or non-standard sizeof the locating flanges 44f of the stationary component. The sealsurfaces 34f will lie concentric about the sealing surface of the rotor12f because any out-of-roundness, eccentricities, or non-standard sizesof the locating flanges 44f has been compensated for by radialadjustment of surfaces 64f whereby seal segments 32f form a complete,substantially perfect annular seal about rotor 12f.

FIG. 20 illustrates a further form of a positive pressure packing ringsegment 32g with a side seal 52g. Except as otherwise noted, the generalconfiguration of this form of seal segment is similar to that of thesegment illustrated in FIGS. 16-19. In this form, however, there isprovided only one pair of leaf springs 62g for each segment with eachspring 62g lying on the opposite side of the neck 48g of the segment.Instead of residing in slots formed along the outer surface of the sideseals, as illustrated in the prior embodiment, springs 62g engage alongthe radially outermost surface of side seal 52g with their opposite endsengaging the underside of flanges 40g. Also, guide rib 54g extends in aslot 56g adjacent an end of the segment 32g. In this form and instead ofproviding locating surfaces formed on the side seals as in the previousembodiment, the adjustment is provided by locating elements E, in thispreferred form, comprising T-pads 71g carried by segments 32g. Thus, apair of T-pads 71g are slidable axially into corresponding slots 69gthrough the segment, particularly through the segment flanges 40g and aportion of neck 48g. Locating surfaces 47g of elements E are spacedradially inwardly of the underside of flanges 40g for engagement withthe radially outermost surfaces of side seals 52g. By adjusting theradial extent of these locating surfaces on elements E, for example byadding or removing material from those surfaces at differentcircumferential locations about the segment to compensate forout-of-roundness, eccentricity or non-standard size of the locatingflanges 44G, a uniform radial clearance between the seal faces 38g andthe sealing surface of rotor shaft 12g may be obtained. Note that, inthis form of the invention, the springs 62g are captured between theside seals 52G and segment flanges 40g between one locating element Eand the guide rib 54g. The ends of the springs 62G may engage element Eand guide 54g or may be spaced from them.

Also illustrated in FIG. 20 is an end butt seal generally indicated 80,for substantially sealing the end joints between adjacent seal segments32. In this form, the butt seal may comprise a tongue 82 formedintegrally with segment 32g and projecting tangentially therefrom. Theadjoining segment 32g is provided with a recess 84 for receiving tongue82 thereby affording a seal between adjoining segments to prevent escapeof fluid, e.g., steam through the butt joints of the segments. Theprojections may extend from corresponding ends of the segments with therecesses formed in the opposite ends. Alternatively, alternate segmentsmay be provided with the tongues and recesses, respectively.

Also illustrated in FIG. 20 is one of a pair of retaining keys 86carried by the stationary component radially outwardly of the groove forlimiting the extent of circumferential opening of the butt joints of thesegments. Each key 86 is secured to the housing 14G by a bolt 88 andprojects radially inwardly into a slot 90 formed in the end of a segmentadjacent the horizontal joint between the upper and lower turbinehousings. The retainer keys 86 preclude the segments in the upperturbine housing from falling from the groove fit thereof when the upperhousing is removed from the lower housing. The retainer keys alsominimize the amount of opening between the segments in the upperhousing. Thus, with three segments in the upper housing, the retainingkeys limit the opening between a pair of adjoining segments in the upperhousing to a maximum equal to the combined clearance necessary for thetwo butt joints of the three segments to move radially inwardly andoutwardly.

Referring now to the embodiment of FIGS. 21 and 22, there is illustratedanother form of a positive pressure packing ring for a machine diaphragmwhich similarly includes a plurality of segments 32h. As in priorembodiments, each segment includes axially oppositely directed locatingor hook flanges 48h and seal face flanges 38h connected by an axiallyreduced neck 48h extending between those flanges. The compensation oradjustment feature of the present invention is afforded by the provisionof three circumferentially spaced locating elements E having radiallyinwardly directed locating surfaces 47h which are adjustable aspreviously described. Thus, to permit the segment to move radiallyinwardly at a desired circumferential position to provide uniform radialseal clearance about the rotor, the locating surfaces 47h of elements Emay be ground or reduced or conversely to displace the segment radiallyoutwardly for the same purpose the locating surfaces 47h of elements Ecan be increased by adding material. Alternatively, radially smaller orlarger elements E may be provided with different radial locations oflocating surfaces 47h.

It is a feature of this embodiment of the present invention that thesprings 62h are located or constrained between the portions of locatingelements E projecting radially inwardly. Thus, opposite ends of eachspring 62h bear against the sides of circumferentially spaced locatingelements E. It will also be appreciated that, when the adjustments aremade to the locating surfaces of locating elements E, the springdeflection forces change. To restore the spring deflection to thedesigned force level, and where an adjustment to locating elements E hasbeen made, for example, by reducing or grinding the locating surfaces47h, small pockets can be ground in the elements E to accommodate thespring ends. This is schematically illustrated in FIG. 22A where theopposite circumferential sides of the T-pad 71h have been reduced asillustrated by the dashed line 89 to accommodate the ends of springs62h. In this manner, the deflection force of the springs is returned toits originally designed force level. Alternatively, where the locatingsurface of locating elements E has been built up by adding material or aradially larger element E is provided, material can be added to thesides of T-pads 71 h as illustrated in FIG. 22B. In this manner, thespring deflection forces can be restored. As a further alternative, ofcourse, the ends of the springs can be reduced or extended to restorethe spring deflection force.

Referring now to, FIG. 22C, there is illustrated a further form ofpositive pressure packing ring seal similar to the seal illustrated inFIG. 20. In this form, as in FIG. 20, the butt joints 80i of theadjoining segments 32i include the integrally extending tongue 82i withreceiving slot 84i in the end of the adjoining segment 32i.Additionally, the upper diaphragm housing carries a dowel pin 90 whichis receivable in a slot formed in the flange 40i of segment 32i adjacentthe horizontal joint between the upper and lower turbine casings. Dowelpin 90, similarly as the retaining key 86, limits the amount ofcircumferential movement of the butt opening as well as maintains theupper segments from falling out of the upper casing when the upperdiaphragm casing is removed. Dowel pin 90 may also be used with theembodiment of the invention illustrated in FIG. 24 described as follows.

Referring now to FIG. 23, there is illustrated a further embodiment of abutt joint between adjacent segments of any of the types previouslydescribed. In this embodiment, there is provided a slot 81 formed in theneck portion of a ring segment at its end face. The slot receives aspring 83 which biases a tongue 85 outwardly in a tangential directionto project the tongue from of the end face of the segment. The end faceof the adjoining segment forms a surface against which the end of theprojecting tongue 85 abuts. When butt seals of this type are used, theprojecting tongue will thus always project to a maximum extent given thenecessity of the segments to move radially between seal open and sealclosed positions and hence provides an effective seal.

In FIG. 24 there is illustrated a positive pressure packing seal ringincluding a plurality of segments 32j. Each segment 32j as in the priorembodiments, includes axially extending locating or hook flanges 40j,sealing face flanges 38j, and a neck 48j interconnecting the flanges.Also in this embodiment, two locating elements E, in the form ofT-shaped pads 71j are disposed in complementary axially opening slots insegments 32j at adjacent opposite ends thereof, the slots receivingT-shaped pads 71j passing through flanges 40j and neck portion 48j.Springs 62j are located between elements E below flanges 40j and biasthe segments for movement in a radially outward direction. Integralprojecting tongues 82j for reception in corresponding slots 84j are alsoprovided, forming butt seals between adjacent segments.

In this embodiment, as illustrated in FIG. 24a, a fluid, e.g., steampassage 92 opens on the high pressure side of segment 32j into the neckportion 48j. The steam passage 92 opens through the top of the segmentinto the groove cavity or annulus on top of the seal ring. This enableshigh pressure fluid to pass from the high pressure side into the grooveannulus to close the ring segments, i.e., displaces them in the radiallyinward direction. This avoids the necessity of forming steam passages inthe stationary casing for this purpose when field installing ringsegments.

Referring now to FIGS. 25 and 26, there is illustrated a furtherapplication of the present invention to the seal between rotating andstationary components of a turbine wherein the rotating componentcomprises a turbine wheel. In FIG. 26, the buckets of a turbine wheelare illustrated at 100, the buckets 100 having a bucket cover 102.Typically, a tip spill strip segment 104 is secured to the stationarycomponent of the turbine and has a radially inwardly projecting tip 106for forming a seal with the rotary component, i.e., the turbine bucketcover 102. As with the packing ring segments previously described, theseal between the turbine wheel and the tip spill strip segment issubject to the same problems associated with a stationary part aspreviously described, i.e., out-of-round mounting grooves, eccentricityof the mounting grooves or non-standard sized grooves. It will beappreciated from a review of FIG. 25 that a standard tip spill stripsegment 104 includes an axially extending flange 108 for mounting withina groove 110 in a stationary structure 112. In conventional practice, aspring 114 extends about the outer periphery of segments 104 to maintainthe segment 104 in a radially innermost sealing position about thebucket cover.

To accommodate out-of-roundness, eccentricity or non-standard sizing ofgroove 110, in accordance with the present invention, the radial edgesof the mounting flange 108 of the tip spill segments 104, are relievedfor example by machining, as illustrated by the dashed lines 116 in FIG.25. The flange surfaces are functionally replaced by adjusting dowels orkeys 118 which extend axially through the segments 104 atcircumferentially spaced positions. Thus, by adjusting the locatingsurfaces 103 of the dowels which project axially beyond the segment 104to engage the groove fit 110, at circumferentially spaced positionsabout the stationary part, the radial clearance between the seal 106 andbucket cover 102 can be maintained substantially uniform. That is, byadding or subtracting material or providing different sized keys ordowels in the tip spill segment, the segments can be adjusted toaccommodate the out-of-roundness, eccentricity or non-standard sizes ofthe locating fits 102.

The following is a description of the method of assembling the packingrings and installing the packing rings for both the positive pressurepacking rings with side seals illustrated in FIG. 20 hereof and thepositive pressure packing rings without side seals as illustrated inFIGS. 21-24. The packing ring segments with side seals, for example thesegments illustrated in FIG. 20, may be shipped to the installation sitefully assembled using compression tools. This tool is universal for allsegments of this type and, with reference to FIGS. 27 and 28, comprisesa pair of laterally spaced legs 100 having flanges 102 an opposition toone another and joined at their opposite ends by a dowel 104. A threadedscrew 106 extends through a central portion of the dowel between thelegs for engaging the outer surface of the flanges 40. Thus, the flanges102 of the legs engage along the radially inner surface of the sideseals 52 with the screw thread engaging along the outer surface of thesegment. In this manner, the side seals are maintained assembled to thesegments with the springs 62 located between the side seals and flanges40.

When positive pressure packing rings of this type are installed, thestationary grooves often require enlargement. If field machining isrequired for this purpose, the locating flanges 44 may also be checkedfor eccentricity or out-of-roundness and machined to a perfectly roundconfiguration to achieve the uniform radial clearance. In this lattercase, the locating elements of the segments need not be adjusted and theinstallation can go forward without such adjustment. If the stationarygroove does not require enlargement and the groove is eccentric,out-of-round or non-standard in size, the radial adjustment must beperformed. The out-of-roundness, eccentricity or non-standard size ofthe grooves are first determined at each of the circumferentialpositions of the adjustments. Thus, for example with the embodimentillustrated in FIG. 20, oversized or undersized T-shaped pads 21 areprovided and selected depending upon the amount of adjustment necessaryat each circumferential location. The pads can be field ground ormaterial can be added to obtain in-between sizes. Other adjustments maythen be made for example changing the spring length to maintain thecorrect spring force or forming grooves or adding material at the T-padsagainst which the spring ends will abut (see FIGS. 22A and 22B).

Having established the appropriate size of the adjustment, andidentified and/or adjusted the appropriate T-pads 71, T-pads 71 can thebe disposed in the complementary slots at the correct circumferentiallocations and secured in place, for example, by peening or bolting. Whenpeening, only one side of the key is peened although two grooves areprovided as illustrated an FIG. 5, in order to permit reuse of the key.The groove fits of the stationary component are the cleaned.

If integral butt tongues are not provided, the springs 83 are located inslots 81. Butt tongues are then located in the butt tongue spring slotscompressing the springs, the tongues projecting from the ends of thesegments.

If the segments are not delivered at the field installation site inassembled condition, the ring segments may be assembled on site bylocating each segment on a flat surface with its teeth facing upwardly.The wide seal ring may be placed against the ring's neck adjacent thewide shoulder, the crush pins facing outwardly. The wide spring is thenplaced between the side seal and flange 40. This procedure is thenrepeated for the narrow side of the segment. The compression tool isthen placed over one end of the assembly until it is midpoint of thespring length. The tool is then tightened by rotating the thumb screwuntil full closure of the ring is achieved. Another compression tool isthen placed on an end of the packing ring.

The packing segment is then inserted into the groove, free end first,until it hits a compression tool. The tool is then loosened and thepacking ring springs are checked to ensure that they are retained in thesegment cavity. The loose compression tool is then displaced toward theend compression tool as the ring is inserted further into the groove.The second compression tool is then loosened and the ring is completelyinserted into the groove and located in its final, predeterminedposition. The procedures are repeated for each of the remaining segmentsfor each of the housings.

Closed tooth-to-tooth diameter measurements are then taken to check fordesired radial clearances before the rotor is placed back in theturbine. The ring segments are then displaced at the horizontal jointpast the joint and further into the groove. Wedges may then be insertedbetween the packing ring and packing bore to close the rings andtooth-to-tooth diameters of the high teeth may be taken for comparisonwith the measured rotor diameter measurements. The compared clearancesshould be acceptable. The rings are then permitted to slide toward thejoint and the retaining pins or keys are installed in the upper halfpacking rings to prevent the rings from falling during handling.

With respect to the diaphragm packing rings of the positive pressuretype illustrated in FIGS. 21-24, the parts of these segments may beshipped to the installation site in disassembled form. The diaphragmpacking rings are typically installed into existing diaphragm packingdove-tails without enlarging the packing grooves. If the grooves requiremachining for enlargement, then the hook or locating flanges 44 may bemachined to accommodate any out-of-roundness, eccentricity, ornon-standard size. However, if the packing groove enlargement is notrequired and the grooves are out-of-round, eccentric or non-standard,various sizes of elements E, for example the T-pads 71, are selected inaccordance with the necessary adjustment for each of the circumferentialpositions about the turbine. After the appropriate T-pads are selected,and any adjustments to the selected T-pads as necessary have been made,the T-shaped pads may be staked in place as previously described. Thedove-tails may then be cleaned of any foreign matter.

The middle ring segment is then placed on a horizontal surface with itsteeth facing upwardly. The wide and narrow springs are then placed onopposite sides of the packing ring with appropriate adjustments asnecessary as previously described. The packing ring is then insertedinto the diaphragm groove until the springs are engaged in thedove-tail. If the segment has a second set of springs, those springs arethen inserted between the other sets of locating elements E. The ring isthen further inserted into the diaphragm into its final position. Theremaining two-ring segments are then similarly inserted into thediaphragm groove for each housing and the tongue-and-groove fits betweenthe segments should be checked. Similar measurements as previouslydescribed with the segments having side seals may be taken to ensure theconcentricity of the seal faces to the sealing surface of the rotor. Therotor is then disposed in the turbine and the housing reassembled.

While the invention has been described with respect to what is presentlyregarded as the most practical embodiments thereof, it will beunderstood by those of ordinary skill in the art that variousalterations and modifications may be made which nevertheless remainwithin the scope of the invention as defined by the claims which follow.

What is claimed is:
 1. In a machine having a component rotatable aboutan axis and a stationary component including an annular groove aboutsaid axis, said stationary component having at least one axiallydirected locating flange about said axis and in part defining a slotopening into said groove and a plurality of annular segments about saidaxis, each segment having an arcuate seal face, at least one axiallydirected flange for disposition in said groove, and a neck portionreceivable in said slot and interconnecting the seal face and the flangeof said segment, a method of compensating for deviation in radialclearance between said seal faces and the rotatable component from apredetermined substantially uniform radial clearance therebetweencomprising the steps:identifying the extent of the deviation of thelocating flange of the groove from a predetermined radial locationthereof about the axis; and adjusting the flanges of said segmentrelative to the locating flange of the groove in accordance with theextent of said deviation of the locating flange of the groove from saidpredetermined uniform radial location thereof about the axis toestablish a substantially uniform radial clearance about and between theseal faces of the segments and the rotating component.
 2. A methodaccording to claim 1 including the step of inserting a tongue projectingfrom one end of a segment into a receiving slot at an adjoining end ofan adjoining segment to form a seal between the adjoining segments.
 3. Amethod according to claim 1 including the step of providing a stopcooperable between the stationary component and a segment, respectively,to limit movement of said segments in a circumferential direction.
 4. Ina machine having a component rotatable about an axis and a stationarycomponent including an annular groove out-of-round or eccentric aboutsaid axis, said stationary component having a pair of axially inwardlydirected locating flanges out-of-round or eccentric about said axis anddefining the out-of-roundness or eccentricity of said groove about saidaxis, and a plurality of annular segments about said axis, each segmenthaving an arcuate seal face, a pair of flanges directed axially awayfrom one another and disposed in said groove, and a neck portionreceived in said slot and interconnecting the seal face and pair offlanges, a method of compensating for out-of-roundness or eccentricityof the locating flanges of said groove about said axis, comprising thesteps of:identifying the extent of out-of-roundness of eccentricity ofthe locating flanges of the groove; and adjustably spacing the flangesof said segments relative to the locating flanges of the groove inaccordance with the extent of out-of-roundness or eccentricity of theflanges of the groove about the axis such that the seal face of thesegments provide a substantially uniform radial clearance with therotating component.
 5. A method according to claim 4 including locatingat least a pair of locating surfaces at circumferentially spacedpositions about each said segment for spacing the flanges of saidsegments relative to the locating flanges of the groove and adjustingthe radial location of the locating surfaces in accordance with theextent of the out-of-roundness or eccentricity of the locating flangesof the groove.
 6. A method according to claim 5 including forming saidsegments and said groove such that said segments are movable in a radialdirection between first and second positions, biasing said segments formovement into said first position, and adjusting said locating surfacesto locate said segment flanges relative to said locating flanges of thegroove to establish a substantially uniform radial clearance about andbetween the rotating component and the segment seal faces.
 7. In amachine having a component rotatable about an axis and a stationarycomponent including an annular groove about said axis, said stationarycomponent having at least one axially directed locating flange aboutsaid axis and in part defining a slot opening into said groove and aplurality of annular segments about said axis, each segment having anarcuate seal face, at least one axially directed flange for dispositionin said groove, and a neck portion receivable in said slot andinterconnecting the seal face and the flange of said segment, a methodof compensating for deviation in radial clearance between said sealfaces and the rotatable component from a predetermined substantiallyuniform radial clearance therebetween comprising the steps:identifyingthe extent of the deviation of the locating flange of the groove from apredetermined radial location thereof about the axis; adjusting theflanges of said segment relative to the locating flange of the groove inaccordance with the extent of said deviation of the locating flange ofthe groove from said predetermined radial location thereof about theaxis to establish a substantially uniform radial clearance about andbetween the seal faces of the segments and the rotating component; andlocating at least a pair of locating surfaces at circumferentiallyspaced positions about each said segment for spacing the flanges of saidsegments relative to the locating flange of the groove and adjusting thelocating surfaces in accordance with the extent of the deviation of theflange of the groove from a predetermined radial location thereof aboutthe axis to adjustably space the flanges of said segments relative tothe locating flange.
 8. A method according to claim 7 including formingsaid segments and said groove such that said segments are movable in aradial direction between first and second positions, biasing saidsegments for movement into said first position and adjusting saidlocating surfaces to locate said segment flanges relative to saidlocating flange of the groove to establish a substantially uniformradial clearance about and between the rotating component of the segmentseal faces.
 9. In a machine having a component rotatable about an axisand a stationary component including an annular groove about said axis,said stationary component having at least one axially directed locatingflange about said axis and in part defining a slot opening into saidgroove and a plurality of annular segments about said axis, each segmenthaving an arcuate seal face, at least one axially directed flange fordisposition in said groove, and a neck portion receivable in said slotand interconnecting the seal face and the flange of said segment, amethod of compensating for deviation in radial clearance between saidseal faces and the rotatable component from a predeterminedsubstantially uniform radial clearance therebetween comprising thesteps:identifying the extent of the deviation of the locating flange ofthe groove from a predetermined radial location thereof about the axis;adjusting the flanges of said segment relative to the locating flange ofthe groove in accordance with the extent of said deviation of thelocating flange of the groove from said predetermined radial locationthereof about the axis to establish a substantially uniform radialclearance about and between the seal faces of the segments and therotating component; and wherein said deviation of the locating flange ofthe groove from the determined radial location thereof, withoutcorrection, constitutes an out-of-roundness of said locating grooveabout said axis, and including identifying the extent ofout-of-roundness of the locating flange of the groove, and adjusting thespacing of the flanges of said segments relative to the locating flangeof the groove in accordance with the extent the locating flange isout-of-round about the axis to provide said correction thereby toestablish substantial concentricity of said seal faces relative to therotating component.
 10. In a machine having a component rotatable aboutan axis and a stationary component including an annular groove aboutsaid axis, said stationary component having at least one axiallydirected locating flange about said axis and in part defining a slotopening into said groove and a plurality of annular segments about saidaxis, each segment having an arcuate seal face, at least one axiallydirected flange for disposition in said groove, and a neck portionreceivable in said slot and interconnecting the seal face and the flangeof said segment, a method of compensating for deviation in radialclearance between said seal faces and the rotatable component from apredetermined substantially uniform radial clearance therebetweencomprising the steps:identifying the extent of the deviation of thelocating flange of the groove from a predetermined radial locationthereof about the axis; adjusting the flanges of said segment relativeto the locating flange of the groove in accordance with the extent ofsaid deviation of the locating flange of the groove from saidpredetermined radial location thereof about the axis to establish asubstantially uniform radial clearance about and between the seal facesof the segments and the rotating component; and wherein said deviationof the locating flange of the groove from the determined radial locationthereof without correction, constitutes an eccentricity of said locatinggroove about said axis, and including identifying the extent ofeccentricity of the locating flange of the groove and adjusting thespacing of the flanges of said segments relative to the locating flangeof the groove in accordance with the extent the locating flange iseccentric about the axis to provide said correction thereby to establishsubstantial concentricity of said seal faces relative to the rotatingcomponent.